The more parsimonious explanation is that commercial jet engine production is downstream of commercial airbody production and China's currently limited by COMAC's scaling woes. All the money and talent in the world can't replicate real users generating real data that you can use to improve. I'd argue the opposite that jet engines have a market structure that's uniquely terrible for traditional free market societies.…
The correct answer to this is to break up consolidated markets with antitrust. Are there only two airframe manufacturers left? Then chop them into smaller pieces so there are more. Reduce vertical integration so that it gets easier for new entrants to compete at any given part of the supply chain without needing to duplicate the entire thing themselves. Let each of the spin offs start with a non-exclusive license to the no longer existent parent company's technology so they all have the chance to iterate on it and compete for providing it.
And don't let them buy each other again.